1. Field of the Invention
The present invention relates to an apparatus for positioning an electronic component holder head and an apparatus for transferring an electronic component (xe2x80x9cECxe2x80x9d).
2. Related Art Statement
Japanese Patent Application laid open for inspection under Publication No. 2-69999 discloses an EC holder head which is employed by an EC mounting system for mounting one or more ECs on an object such as a printed circuit board (xe2x80x9cPCBxe2x80x9d). The prior EC mounting system includes a rotatable table which is intermittently rotatable about a vertical axis line, and a plurality of head supporting devices which are supported by the rotatable table such that the head supporting devices are equiangularly spaced from each other about the vertical axis line of- the rotatable table and such that each of the head supporting devices is movable in a direction parallel to the vertical axis line. Each of the head supporting devices supports an EC holder head such that the EC holder head extends parallel to the vertical axis line of the rotatable table and such that the EC holder head is rotatable about an axis line thereof. As the rotatable table is intermittently rotated, each of the head supporting devices is sequentially stopped at each of the same number of stop stations as that of the supporting devices. At an EC sucking station as one of the stop stations, each of the head supporting devices is moved up and down by an elevating and lowering device, so that the EC holder head supported by said each head supporting device sucks up an EC from an EC supplying device. Meanwhile, at an image taking station as one of the stop stations, an image of the EC held by the EC holder head is taken by an image taking device, so that an angular position error of the EC about an axis line of the EC holder head is calculated based on the image data provided by the image taking device and the calculated angular position error of the EC is corrected by rotating the EC holder head about the axis line thereof. After the angular position error of the EC is corrected, the head supporting device is moved to an EC mounting station as one of the stop stations, where the head supporting device is lowered by another elevating and lowering device, so that the EC holder head supported thereby mounts the EC on a PCB.
However, the above-identified prior EC mounting system can stop each of the head supporting devices at only one circumferential stop position in each of the plurality of stop stations, and cannot change or move the only one circumferential stop position in the circumferential direction of the rotatable table. Likewise, the prior EC mounting system can position each of the EC holder heads at only one position relative to the corresponding head supporting device in the direction parallel to the vertical axis line of the rotatable table, and cannot change or move the only one relative position in the direction parallel to the vertical axis line. In addition, the prior EC mounting system can move each of the EC holder heads along only one movement path and cannot change or move at least a portion of the movement path to another path whose position in a direction normal to that portion of the movement path is different from that of the portion of the movement path.
It is therefore an object of the present invention to provide an apparatus wherein at least one of (a) a circumferential or rotating-direction stop position of a rotary member which carries an EC holder head and is rotatable about an axis line while describing a circular locus and (b) a position of the EC holder head relative to the rotary member in a direction parallel to the axis line is selectively changeable.
It is another object of the present invention to provide an apparatus which includes a plurality of rotary members which are rotatable about a common axis line independently of each other and each of which carries an EC holder head and wherein at least one of (a) a rotating-direction position of at least one of the rotary members and (b) a position of the EC holder head carried by at least one of the rotary members relative to said one rotary member in a direction parallel to the common axis line is selectively changeable.
It is another object of the present invention to provide an apparatus which includes a drive cam and at least one cam follower which cooperate with each other to rotate a rotary member and wherein a rotating-direction stop position of the rotary member is easily and selectively changeable.
It is another object of the present invention to provide an apparatus wherein a stationary cam and at least one cam follower are employed for easily and selectively changing a position of an EC holder head relative to an rotary member in a direction parallel to an axis line about which the rotary member is rotatable.
It is another object of the present invention to provide an apparatus which includes an EC holder head which is movable along a circular movement path or an EC holder head which is movable along a straight movement path and wherein at least one of (a) an on-path stop position on the circular or straight movement path and (b) an intersecting-direction stop position spaced from the circular or straight movement path in a direction intersecting the movement path is selectively changeable.
It is another object of the present invention to provide an EC transferring apparatus which can select, as at least a portion of a movement path along which an EC holder head is movable, one of a plurality of selectable paths which have different positions, respectively, in a direction intersecting that portion of the movement path.
The present invention provides an EC holder head positioning apparatus, an EC transferring apparatus, and an EC mounting system which have one or more of the technical features which are described below in respective paragraphs given parenthesized sequential numbers (1) to (25). Any technical feature which includes another technical feature shall do so by referring, at the beginning, to the number given to that technical feature. Thus, two or more of the following technical features may be combined, if appropriate. Each technical feature may be accompanied by a supplemental explanation, as needed.
(1) According to a first feature of the present invention, there is provided an apparatus for positioning each of a plurality of electronic component holder heads each for holding an electronic component, at a selected one of a plurality of positions of at least one stop station, comprising a plurality of rotary members each of which is rotatable about a common axis line and is stoppable at the at least one stop station, the electronic component holder heads being carried by the rotary members, respectively, such that each of the holder heads is movable relative to a corresponding one of the rotary members in a direction parallel to the common axis line; and at least one of (a) a circumferential position selecting device which selects, for the stop station, one of a plurality of circumferential positions which are spaced from each other in a direction of rotation of the rotary members about the common axis line, so that at least one of the rotary members is stopped at the selected circumferential position and accordingly the electronic component holder head carried by the one rotary member is positioned at the selected one position, and (b) an axial position selecting device which selects, for the stop station, one of a plurality of axial positions which are spaced from each other in the direction parallel to the common axis line, so that at least one of the holder heads is positioned at the selected axial position as the selected one position. The present positioning apparatus can select one of the plurality of circumferential positions and/or one of the plurality of axial positions. Accordingly, in the case where the present positioning apparatus is employed by, e.g., an EC mounting system having an EC sucking station and an EC mounting station, the present apparatus can select, as an EC sucking position at the EC sucking station or as an EC mounting position at the EC mounting station, one of the plurality of circumferential positions so that at least one of the rotary members, i.e., the EC holder head carried on said one rotary member is stopped at the selected one circumferential position as the EC sucking position or as the EC mounting position. In addition, depending upon a dimension of an EC as measured in the direction parallel to the common axis line, the present apparatus can select, as a stroke of movement of the EC holder head for sucking the EC or mounting the EC, one of the plurality of axial positions spaced from each other in the direction parallel to the common axis line, so that the EC holder head is moved to, and positioned at, the selected one axial position corresponding to the stroke of movement of the EC holder head. Thus, the present apparatus contributes to improving the EC mounting efficiency of the EC mounting system.
(2) According to a second feature of the present invention which includes the first feature (1), the positioning apparatus further comprises a rotary member supporting device which supports the rotary members such that the rotary members are rotatable about the common axis line independently of each other; and a rotary member rotating device which rotates the rotary members supported by the rotary member supporting device, independently of each other. Since the rotary members are rotatable independently of each other, the present positioning apparatus can rotate one of the rotary members while having another rotary member stopped at a stop station. Therefore, as will be described on a preferred embodiment of the present invention, the present apparatus can shorten a transferring pitch at which each of the rotary members is transferred from one stop station to the next stop station. Since this technical feature is combined with the above-indicated feature that the present apparatus can select one of the plurality of circumferential positions and/or one of the plurality of axial positions, the present apparatus can enjoy a high EC transferring efficiency of the EC holder heads.
(3) According to a third feature of the present invention which includes the second feature (2), the rotary member rotating device comprises a plurality of cam followers each of which is connected to a corresponding one of the rotary members; and at least one drive cam which has a cam groove engageable with each of the cam followers and which is rotatable about an axis line to move the each cam follower and thereby rotate a corresponding one of the rotary members about the common axis line, at least a portion of the cam groove having a width which permits the each cam follower to be moved in a direction of the width, and the circumferential position selecting device comprises a plurality of circumferential-direction pressing devices each of which selectively presses a corresponding one of the cam followers against each of a pair of opposed side surfaces of the cam groove. In the case where the cam groove of the drive cam includes an inclined portion which is inclined relative to the axis line of the cam, and a perpendicular portion extending in a direction perpendicular to the axis line, each of the rotary members is rotated when the drive cam is rotated with the cam follower connected to said each rotary member being engaged with the inclined portion of the cam groove, and is stopped when the drive cam is rotated with the cam follower being engaged with the perpendicular portion of the cam groove. Therefore, two stop positions which are spaced from each other in the direction of rotation of the rotary members can be defined by employing a cam groove having a width which permits each cam follower to be moved in a direction of the width. That is, one of the two stop positions corresponds to the state in which each cam follower is pressed against one of the two opposed side surfaces of the cam groove, and the other stop position corresponds to the state in which each cam follower is pressed against the other side surface of the cam groove. Thus, each rotary plate can be selectively positioned at one of the two stop positions by pressing, using a rotating-direction or circumferential-direction pressing device, the cam follower connected to each rotary plate against a corresponding one of the two opposed side surfaces of the cam groove. Since in the present positioning apparatus the plurality of circumferential positions are defined by providing a drive cam employed for rotating each rotary member, with a cam groove having a width which permits each cam follower to be moved in a direction of the width, the present apparatus can select one of the plurality of circumferential positions in a simple and low-cost manner.
(4) According to a fourth feature of the present invention which includes the second feature (2), the rotary member rotating device comprises a plurality of pairs of cam followers each pair of which are connected to a corresponding one of the rotary members, respectively; and at least one drive cam which has a cam rib engageable with each pair of cam followers out of the pairs of cam followers and which is rotatable about an axis line to move the each pair of cam followers and thereby rotate a corresponding one of the rotary members about the common axis line, at least a portion of the cam rib of the drive cam having a thickness which permits the each pair of cam followers to be moved in a direction of the thickness, and the circumferential-position selecting device comprises a plurality of circumferential-direction pressing devices each of which selectively presses each of the two cam followers of a corresponding one pair of the pairs of cam followers against a corresponding one of a pair of opposite side surfaces of the cam rib. In the case where the cam rib of the drive cam includes an inclined portion which is inclined relative to the axis line of the cam, and a perpendicular portion extending in a direction perpendicular to the axis line, each of the rotary members is rotated when the drive cam is rotated with the pair of cam followers connected to said each rotary member being engaged with the inclined portion of the cam rib, and is stopped when the drive cam is rotated with the pair of cam followers being engaged with the perpendicular portion of the cam rib. Therefore, two stop positions which are spaced from each other in the direction of rotation of the rotary members can be defined by employing a cam rib having a width which permits each pair of cam followers to be moved in a direction of the width. That is, one of the two stop positions corresponds to the state in which one of the two cam followers of each pair is pressed against one of two opposite side surfaces of the cam rib, and the other stop position corresponds to the state in which the other cam follower of each pair is pressed against the other side surface of the cam rib. Thus, each rotary plate can be selectively positioned at one of the two stop positions by pressing, using a circumferential-direction pressing device, one of the two cam followers connected to each rotary plate against a corresponding one of the two opposite side surfaces of the cam rib.
(5) According to a fifth feature of the present invention which includes any one of the first to fourth features (1) to (4), the positioning apparatus further comprises a stationary cam which has a cam groove formed along a cylindrical surface having a center line on the common axis line; and a plurality of cam followers each of which is connected to a corresponding one of the electronic component holder heads and is engageable with the cam groove of the stationary cam, at least a portion of the cam groove of the stationary cam having a width which permits the each cam follower to be moved in a direction of the width, and the axial position selecting device comprises a plurality of axial-direction pressing devices each of which selectively presses a corresponding one of the cam followers against each of a pair of opposed side surfaces of the cam groove. In the present positioning apparatus, each of the cam followers is pressed against one of the pair of opposed side surfaces of the cam groove and, when each of the rotary members is rotated, the cam follower connected to the EC holder head carried by said each rotary member is moved along said one side surface of the cam groove. The pair of opposed side surfaces of the cam groove are spaced from each other in the direction parallel to the common axis line, and the portion of the cam groove which has a width which permits each cam follower to be moved in a direction of the width, defines two axial positions which are spaced from each other in the direction parallel to the common axis line. Therefore, in the case where a portion of the cam groove which corresponds to a stop station has a width which permits each cam follower to be moved in a direction of the width, the present positioning apparatus can select one of the two axial positions at the stop station.
(6) According to a fifth feature of the present invention which includes the fifth feature (5), the cam groove of the stationary cam includes a portion whose position in the direction parallel to the common axis line continuously changes. In the present positioning apparatus, when each of the cam followers is moved along the above-indicated portion of the cam groove, the EC holder head to which said each cam follower is connected is moved in the direction of rotation of the rotary members while being moved in the direction parallel to the common axis line (hereinafter, referred to as the xe2x80x9caxial directionxe2x80x9d). Thus, the stop positions at which the EC holder head is stopped in the axial direction at one of a plurality of stop stations may differ from those at another stop station. Each of the axial-direction pressing devices can press a corresponding one of the cam followers against a selected one of the opposed side surfaces of the cam groove, thereby selecting a corresponding one of the stop positions at each of the stop stations. For example, in the case where the present positioning apparatus is employed by an EC mounting system which includes an EC supplying device and an EC mounting device and wherein the EC supplying and mounting devices are provided at different height positions, respectively, the height difference between the two devices can be compensated for by moving each of the EC holder heads in the direction parallel to the common axis line which extends vertically. In the case where the present positioning apparatus is employed by an EC mounting system wherein an EC supplying device and an EC mounting device are provided at the same height position or level, or wherein an EC supplying device and an EC mounting device can be moved up and down by respective elevating and lowering devices, respectively, the cam groove of the stationary cam need not include any portion whose position in the axial direction continuously changes, because there is no need to move each EC holder head in the axial direction. In the latter case, the stationary cam may have the cam groove whose position in the axial direction does not change at all. This is also the case with the EC holder head positioning apparatus wherein the stationary cam has a cam rib or ridge in place of the cam groove.
(7) According to a seventh feature of the present invention which includes any one of the first to fourth features (1) to (4), the positioning apparatus further comprising a stationary cylindrical cam which has a cam rib formed along a cylindrical surface having a center line on the common axis line; and a plurality of pairs of cam followers each pair of which are connected to a corresponding one of the electronic component holder heads and is engageable with the cam rib of the stationary cam, at least a portion of the cam rib of the stationary cam having a thickness which permits the each pair of cam followers to be moved in a direction of the thickness, and wherein the axial position selecting device comprises a plurality of axial-direction pressing devices each of which selectively presses each of the two cam followers of a corresponding one pair of the pairs of cam followers against a corresponding one of a pair of opposite side surfaces of the cam rib. The xe2x80x9cthickxe2x80x9d portion of the cam rib that is other than the xe2x80x9cthinxe2x80x9d portion thereof which has the thickness which permits each pair of cam followers to be moved in the direction of the thickness, may have a thickness which is slightly greater than the distance between the two cam followers in the direction of the thickness of the xe2x80x9cthinxe2x80x9d portion, so that the two cam followers may engage the opposite side surfaces of the cam rib, respectively. In this case, each of the EC holder heads can be moved along the cam rib without any rattling in the axial direction. Although only one of the two cam followers is pressed against a corresponding one of the two side surfaces of the cam rib by the axial-direction pressing device, the two cam followers can be moved along the cam rib while sandwiching the rib without any spaces provided therebetween. The thickness of the xe2x80x9cthinxe2x80x9d portion of the cam rib is smaller than the distance between the two cam followers in the direction parallel to the direction of the thickness of the xe2x80x9cthinxe2x80x9d portion, i.e., the axial direction. Along only the xe2x80x9cthinxe2x80x9d portion of the cam rib, the two cam followers are moved while only one of the two followers is pressed against, and engaged with, a corresponding one of the two side surfaces of the rib by the axial-direction pressing device. Thus, depending upon which one of the two cam followers is pressed against the corresponding one of the two side surfaces of the cam rib, the present positioning apparatus can select, for each EC holder head, one of two axial positions which are distant from each other by a distance equal to the difference between the thickness of the xe2x80x9cthickxe2x80x9d portion of the cam rib and the thickness of the xe2x80x9cthinxe2x80x9d portion of the same.
(8) According to an eighth feature of the present invention which includes the seventh feature (7), the cam rib of the stationary cam includes a portion whose position in the direction parallel to the common axis line continuously changes. Like the positioning apparatus in accordance with the above-indicated sixth feature (6), the present positioning apparatus can select, for each of a plurality of stop stations, one of a plurality of stop positions at which each of the EC holder heads is stopped in the axial direction.
(9) According to a ninth feature of the present invention which includes any one of the first and fifth to eight features (1), (5) to (8), the rotary members are supported on a common, intermittently rotatable table such that each of the rotary members is selectively movable to a plurality of positions thereof located on a circle having a center on the common axis line, and wherein the circumferential position selecting device comprises a plurality of rotary member moving devices each of which selectively moves a corresponding one of the rotary members to one of the plurality of positions thereof.
(10) According to a tenth feature of the present invention which includes any one of the third to eight features (3) to (8), the at least one drive cam comprises at least one concave globoidal cam having an outer circumferential surface which is defined by a locus which is described by a circular arc having a center on the common axis line when the circular arc is rotated about a circular-arc axis line which is perpendicular to the common axis line and which is positioned relative to the circular arc and the common axis line such that the circular arc is interposed between the circular-arc axis line and the common axis line. The outer circumferential surface of the concave globoidal cam contains the circular arc having the center on the common axis line. Therefore, when the globoidal cam which has an appropriate cam surface including a cam groove or a cam rib is rotated about an axis line thereof, the cam follower or followers which is or are engaged with the cam groove or rib is or are moved by the rotation of the cam, so the rotary member to which the cam follower or followers is or are connected is rotated about the common axis line over an angle corresponding to the length of the cam in the direction of rotation of the rotary members.
(11) According to an eleventh feature of the present invention which includes any one of the third to tenth features (3) to (10), at least one of the circumferential-direction pressing devices comprises a fluid-pressure-operated cylinder device. In this case, the circumferential-direction pressing devices can be produced at low cost. The fluid-pressure-operated cylinder device may be a double-acting air cylinder device.
(12) According to a twelfth feature of the present invention which includes any one of the fifth to eleventh features (5) to (11), at least one of the axial-direction pressing devices comprises a fluid-pressure-operated cylinder device. The fluid-pressure-operated cylinder device may be a double-acting air cylinder device.
(13) According to a thirteenth feature of the present invention which includes any one of the fifth to twelfth features (5) to (12), the stationary cam includes a movable portion which is movable in the direction parallel to the common axis line, and wherein the apparatus further comprises a movable portion moving device which moves the movable portion of the stationary cam and thereby moves at least one of the electronic component holder heads in the direction parallel to the common axis line. The movable portion of the stationary cam has a cam groove or a cam rib which provides part of the cam groove or rib of the stationary cam. As each of the rotary members is rotated, the cam follower or followers engages or engage the cam groove or rib of the movable portion. In this state, if the movable portion is moved by the movable portion moving device, the EC holder head carried on the rotary member is moved in the axial direction.
(14) According to a fourteenth feature of the present invention which includes any one of the first to thirteenth features (1) to (13), each of the electronic component holder heads comprises a sucking pipe which sucks and holds, by vacuum, the electronic component.
(15) According to a fifteenth feature of the present invention, there is provided an apparatus for selectively positioning at least one electronic component holder head for holding an electronic component, at a selected one of a plurality of positions of at least one station, comprising a holder head moving and stopping device which moves the electronic component holder head along a predetermined movement path and stops the holder head at the at least one stop station on the movement path; and at least one of (a) an on-path stop position selecting device which selects, for the stop station, one of a plurality of on-path stop positions on the movement path, so that the electronic component holder head is stopped, and accordingly positioned, at the selected on-path stop position as the selected one position, and (b) an intersecting-direction stop position selecting device which selects, for the stop station, one of a plurality of intersecting-direction stop positions which are spaced from each other in a direction intersecting the movement path, so that the electronic component holder head is stopped, and accordingly positioned, at the selected intersecting-direction stop position as the selected one position. The movement path of the EC holder head is not limited to the circular path employed in the EC holder head positioning apparatus in accordance with the first feature (1), but may be a curve other than the circular arc, or a straight line, or a composite of one or more curves and one or more straight lines. For example, the EC holder head may be mounted on a movable member which is movable along a straight movement path and is stoppable at each of a plurality of stop stations on the movement path, and a plurality of stop positions may be provided for at least one of the stop stations. In this case, the present positioning apparatus can select one of the stop positions so that the movable member or the EC holder head may be stopped at the selected stop position. A head moving device which moves the EC holder head may be provided on the movable member. In this case, the positioning apparatus can select one of a plurality of stop positions, by operating the moving device to move the head holder to a selected one of a plurality of positions on the movable member. The movable member may support another or second movable member which carries the EC holder head, such that the second movable member is movable along a straight line perpendicular to the straight movement path on a common plane. In this case, the EC holder head can be moved to any desired position on the common plane by the combination of respective movements of the two movable members. The positioning apparatus can select one of a plurality of stop positions at which the EC holder head is stopped, by moving one of the two movable members to a selected one of a plurality of stop positions therefor and moving the other movable member to a selected one of a plurality of stop positions therefor. An EC holder head moving device may be mounted on the second movable member so as to move the EC holder head to a select one of a plurality of stop positions. In the case where the present positioning apparatus is employed by an EC mounting system including an EC supplying device which utilizes a palette for supplying ECs, the EC holder head and the palette may be moved in respective directions perpendicular to each other in a common plane, so that the EC holder head may pick up an EC accommodated in each of a number of EC accommodating pockets of the palette. Alternatively, each of the head and the palette may be moved in both the two directions, so that the head may pick up the ECs from the palette. Moreover, one of the head and the palette may be moved in only one direction and the other may be moved in both the two directions, so that the head may pick up the ECs from the palette. In either case, the positioning apparatus can select one of the stop positions at each of which the EC holder head is stoppable, thereby selecting one of a plurality of EC pick-up positions at each of which the EC holder head can pick up an EC from the palette. This arrangement contributes to reducing the cumulative distances of movement of the palette. The intersecting direction in which the stop positions are spaced from each other may be any direction intersecting the movement path of the EC holder head, for example, a vertical direction. In the case where the EC holder head is supported on a movable member which is movable along the movement path, such that the holder head is movable on the movable member in a direction perpendicular to the movement path, the intersecting direction may be a direction which is perpendicular to both the movement path and the direction in which the EC holder head is movable on the movable member, or a direction which is perpendicular to the movement path and is parallel to the direction of movement of the EC holder head on the movable member. The present EC holder head positioning apparatus can select, for a stop station, one of a plurality of stop positions at each of which the EC holder head is stoppable when the head is moved along the movement path which may contain a straight line and/or a curve. Therefore, irrespective of the kind of the EC mounting apparatus which employs the present positioning apparatus, the positioning apparatus contributes to improving the EC mounting efficiency of the mounting apparatus.
(16) According to a sixteenth feature of the present invention which includes the fifteenth feature (15), the positioning apparatus further comprising a movable member which supports the electronic component holder head such that the holder head is movable in a direction intersecting the movement path and which is movable along the movement path; a stationary cam having a cam groove extending along the movement path; a cam follower which is connected to the movable member such that the cam follower is movable with the holder head and which is engageable with the cam groove of the stationary cam, at least a portion of the cam groove having a width which permits the cam follower to be moved in a direction of the width, and wherein the intersecting-direction stop-position selecting device comprises an intersecting-direction pressing device which selectively presses the cam follower against each of a pair of opposed side surfaces of the cam groove. The intersecting-direction pressing device may comprise a fluid-pressure-actuated cylinder device, such as a double-acting air cylinder device.
(17) According to a seventeenth feature of the present invention which includes the fifteenth feature (15), the positioning apparatus further comprises a movable member which supports the electronic component holder head such that the holder head is movable in a direction intersecting the movement path and which is movable along the movement path; a stationary cam having a cam rib extending along the movement path; a pair of cam followers which are connected to the movable member such that the pair of cam followers are movable with the holder head and which are engageable with the cam rib of the stationary cam, at least a portion of the cam rib having a thickness which permits the pair of cam followers to be moved in a direction of the thickness, and wherein the intersecting-direction stop-position selecting device comprises an intersecting-direction pressing device which selectively presses each of the two cam followers of the pair against a corresponding one of a pair of opposite side surfaces of the cam rib. The intersecting-direction pressing device may comprise a fluid-pressure-actuated cylinder device, such as a double-acting air cylinder device.
(18) According to an eighteenth feature of the present invention which includes any one of the fifteenth to seventeenth features (15) to (17), the electronic component holder head comprises a sucking pipe which sucks and holds, by vacuum, the electronic component.
(19) According to a nineteenth feature of the present invention, there is provided an apparatus for transferring an electronic component, comprising at least one electronic component holder head which holds an electronic component; a holder head moving device which moves the electronic component holder head along a predetermined movement path; and a path selecting device which selects, as at least a portion of the movement path, one of a plurality of selectable paths which have different positions, respectively, in a direction intersecting the portion of the movement path, so that the electronic component holder head is moved along the movement path including the selected one selectable path. In the case where a stop station is provided on the above-indicated portion of the movement path, the present EC transferring apparatus can select, for the stop station, one of a plurality of stop positions at each of which the EC holder head is stoppable. However, this feature is not essential to the present EC transferring apparatus. For example, the EC holder head is not essentially required to be stopped at an image taking station where an image of an EC held by the holder head is taken for confirming the kind of the EC and/or detecting the possible position errors of the EC held by the holder head. That is, it is possible to take an image of the EC being moved. However, if the kind of one EC held by the EC holder head is different from that of another EC held by the holder head, the distance between an image taking device and the surface of each EC whose image is to be taken by the image taking device at the image taking station may not coincide with the focal length of the image taking device. In this case, the above distance may be so changed as to coincide with the focal length, by changing at least a portion of the movement path along which the EC holder head is moved. The present EC transferring apparatus may be advantageously used in this way, as well. The movement path may be a circular arc, a straight line, a curve other than the circular arc, or a composite of those lines. The intersecting direction may be a direction perpendicular to the above portion of the movement path, such as a vertical direction.
(20) According to a twentieth feature of the present invention which includes the nineteenth feature (19), the transferring apparatus further comprises an image taking device which is provided in association with the portion of the movement path and which takes an image of the electronic component held by the electronic component holder head.
(21) According to a twenty-first feature of the present invention which includes the twentieth feature (20), the image taking device comprises a line sensor which takes, as the image of the electronic component, a set of respective images of contiguous linear portions of the component as the component is moved. The line sensor comprises a number of image pick-up elements which are arranged in a straight array extending in a direction intersecting the direction in which an EC is moved, and takes an image of a linear portion of the EC at regular intervals of time as the EC is moved. Thus, the line sensor takes, as the image of the EC, a set of respective images of the contiguous linear portions of the EC as the EC is moved. When the EC finishes passing by the line sensor, the line sensor finishes taking the entire image of the EC. Thus, a two-dimensional image of the EC is obtained by the combination of the iterative linear-image taking of the line sensor and the movement of the EC held by the EC holder head.
(22) According to a twenty-second feature of the present invention which includes the twentieth feature (20), the image taking device comprises a high-speed camera which emits, when the electric component held by the electronic component holder head passes, a single flashlight toward the component for so short a time that an amount of movement of the component during the time is negligible, and which takes the image of the component exposed to the single flashlight. For example, in the case where the high-speed camera has a stroboscope, the stroboscope emits a strong flashlight toward an EC which is passing by the camera, so that the camera takes an image of the EC. Although the EC is moving, the camera can take an image of the EC, as if the EC were stopped, by employing a very high shutter speed or a very short light-emitting time.
(23) According to a twenty-third feature of the present invention, there is provided a system for mounting an electronic component on an object, comprising an electronic component holder head positioning apparatus according to the first feature (1); an electronic component supply device which is provided at a first one of a plurality of stop stations comprising the at least one stop station and which supplies an electronic component to each of the electronic component holder heads so that the each holder head holds the electronic component; and an object supporting and positioning device which is provided at a second one of the stop stations and which supports and positions an object on which the electronic component held by the each holder head is to be mounted.
(24) According to a twenty-fourth feature of the present invention, the mounting system further comprises an image taking device which is provided at a third one of the stop stations and which takes an image of the electronic component held by the each holder head.
(25) According to a twenty-fifth feature of the present invention, there is a system for mounting an electronic component on an object, comprising an electronic component holder head positioning apparatus according to the feature (15); an electronic component supply device which is provided at a first one of a plurality of stop stations comprising the at least one stop station and which supplies an electronic component to each of the electronic component holder heads so that the each holder head holds the electronic component; and an object supporting and positioning device which is provided at a second one of the stop stations and which supports and positions an object on which the electronic component held by the each holder head is to be mounted.